Dr Sam George

Consultant Anaesthesia & Intensive care

Essential questions before IV fluid prescription 1. Does the patient need any prescription at all today?

2. If so, does the patient need this for a. resuscitation, b. replacement of losses, or c. merely for maintenance?

3. What is the patient’s current fluid and electrolyte status a. Does the patient have a deficit or excess of Na, Cl, K or water?

4. Which is the simplest, safest, and most effective route of administration?

5. What is the most appropriate fluid to use and how is that fluid distributed in the body?

Physiology

Water comprises 60% of the body weight of an average adult,

the total body water is divided functionally into the extracellular (ECF = 20% of body

weight) and the intracellular fluid spaces (ICF = 40% of

body weight)

Physiology

cell membrane with its active sodium pump, which ensures that sodium remains largely in the ECF.

The cell, however, contains large anions such as protein and glycogen, which cannot escape and, therefore, draw in K+ ions to maintain electrical neutrality (Gibbs-Donnan equilibrium)

You want to maintain this Balance

The types of IV fluids Crystalloid – a term used commonly to describe

all clear glucose and/or salt containing fluids for intravenous use (e.g. 0.9% saline, Hartmann’s solution, 5% dextrose, etc.).

Colloid – a fluid consisting of microscopic particles (e.g. starch or protein) suspended in

a crystalloid and used for intravascular volume expansion (e.g. 6% hydroxyethyl starch, 4% succinylated gelatin, 20% albumin, etc.).

Balanced Salt Solution – a crystalloid containing electrolytes in a concentration as

close to plasma as possible (e.g. Ringer’s lactate, Hartmann’s solution, Plasmalyte 148, Sterofundin, etc.).

Crystalloids Colloids

Intravascular vol effect - Better

Interstitial vol. effect Better -

Pulmonary edema Similar potential Similar potential

Peripheral edema Common Uncommon

Reactions Absent Common

Cost Inexpensive Expensive

Composition of commonly used IV crystalloid solutions

Na(mEq/L)

K(mEq/L)

Cl(mEq/L)

HCO3(mEq/L)

Dextrose(gm/L)

mOsm/L

D5W 50 278

½ NS 77 77 143

D51/2NS 77 77 50 350

NS 154 154 286

D5NS 154 154 50 564

Ringers Lactate (RL)

130 4 109 28 50 272

General Principles of fluid prescribing maintain the effective circulatory volume

while attempting to minimize interstitial fluid overload.

incorporate not only daily maintenance requirements, but replacement of any ongoing abnormal losses.

General Principles of fluid prescribing The oral route should be used whenever

possible In acute situations and in the presence of

gastrointestinal dysfunction or large deficits, the intravenous route is the most appropriate.

IV fluids Should be discontinued at the earliest opportunity

The most appropriate fluid to use is that which most closely matches any previous or ongoing losses

What are the Risks

dangerous hyponatraemiaExcessive amounts of 5% dextrose or

4%/0.18% dextrose/saline may cause

sodium, chloride and water overload is a major cause of postoperative morbidityExcessive infusion of 0.9 % saline or

Hartmann’s solution leading to

Pulmonary oedema

Monitoring patients receiving IV fluid

clinical examination fluid balance charts - ensure all sources

of loss, and all intakes (e.g. IV antibiotics) are included on charts.

regular weighing (ideally daily) at least daily U&Es, and in patients with

gastrointestinal (GI) losses, serum magnesium

Monitoring patients receiving IV fluid Assessment of volume status Capillary refill time Pulse rate

Beta blockers/ diltiazem (prevent tachycardia) Blood pressure

Lying and standing Jugular venous pressure Skin turgor (over clavicle) Auscultate

Lungs (pulmonary oedema) Heart sounds (gallop rhythm - hypervolaemia)

Oedema Peripheral/sacral Urine output Weight change to assess water balance

Resuscitation

e.g.blood loss from injury or surgery,plasma loss e.g. from burns or acute pancreatitis, or gastrointestinal or renal losses of salt and water

to restore and maintain the circulation and the function of vital organs. In this situation, the recommendation is to infuse 500 ml (250 ml if cardiac failure) of a balanced crystalloid stat (e.g. Hartmann’s solution or Ringer’s lactate) rapidly.Re assess!

Resuscitation Further administration will depend on

response In the case of intravascular fluid losses,

Blood for Blood, colloids or a combination of colloids and crystalloids are

appropriate to avoid causing excessive rises in oncotic pressure

Large volumes of 0.9% saline are best avoided, except after gastric losses, because of the risk of producing hyperchloraemic metabolic acidosis

Resuscitation

If patients need IV fluid resuscitation, use crystalloids that contain sodium in the range 130–154 mmol/l, with a bolus of 500 ml over less than 15 minutes.

Do not use tetrastarch for fluid resuscitation.

Consider human albumin solution 4–5% for fluid resuscitation only in patients with severe sepsis.

Replacement should include the

daily maintenance requirements plus like-for-like water and electrolyte replacement of any losses.

e.g. from a GI fistula or from nasogastric aspiration, the prescriber should be aware of the

approximate electrolyte content of fluid from various parts of the gastrointestinal tract

Maintenance

aims to restore insensible loss (500-1000 ml), provide sufficient water and electrolytes to maintain normal status of body fluid compartments.sufficient water to enable the kidney to excrete waste products 500-1500 ml

The average person requires 25-35 ml/kg water, 1 mmol/kg Na and 1 mmol/kg K+ per day.

How to assess the patient's likely fluid and electrolyte needs  clinical examination, current medications, clinical monitoring and laboratory investigations

Assessment Volume needs? systolic blood pressure is less than

100 mmHg heart rate is more than 90 beats per minute capillary refill time is more than 2 seconds

or peripheries are cold to touch respiratory rate is more than 20 breaths per

minute National Early Warning Score (NEWS) is

5 or more passive leg raising suggests fluid

esponsiveness.

Assessment Volume needs ? for resuscitation, ABCDE approach measure their venous lactate levels

and/or arterial pH and base excess

How Much?

For routine maintenance alone, restrict the initial prescription to:25–30 ml/kg/day of water and approximately 1 mmol/kg/day of potassium, sodium and chloride and approximately 50–100 g/day of glucose to limit starvation ketosis. Consider using 25–30 ml/kg/day sodium chloride 0.18% in 4% glucose with 27 mmol/l potassium on day 1

How Much?

For patients who are obese, adjust to their ideal body weight. Use lower range volumes per kg (patients rarely need more than a total of 3 litres of fluid per day) and seek expert help if their BMI is more than 40 kg/m2.

How Much?

Consider prescribing less fluid (for example, 20–25 ml/kg/day fluid) for patients who:are older or frailhave renal impairment or cardiac failureare malnourished and at risk of refeeding

syndrome.

 Prescribing more than 2.5 litres per day increases the risk of hyponatraemia.

When to Seek Expert help ? if patients have a complex fluid and/or

electrolyte redistribution issue or imbalance, or significant comorbidity, for example:gross oedemasevere sepsishyponatraemia or hypernatraemiarenal, liver and/or cardiac impairmentpost-operative fluid retention and redistributionmalnourished and refeeding issues

Crystalloids vs Colloids

Proponents of colloid fluid Resuscitation crystalloid solution dilutes plasma

proteinsReduction of plasma oncotic pressureInterstitial pulmonary edema

Requires smaller initial volume, generate prolonged in circulating plasma volume

Isotonic crystalloid – must be infused at least three fold greater volumes- to achieve comparable plasma expansion and hemodynamic stability

Crystalloids vs ColloidsProponents of crystalloid solution

Additional cost and potential risk No benefit with colloids in critical care or general patients and

even in subgroups of trauma, burns or post surgery Removal of colloids- requires longer period than crystalloids in

burn and major surgical patients Coagulopathy – Dextran, HES >20 ml/kg ionised calcium albumin Impaired cross-matching – Dextran Osmotic diuresis LMW dextran HES increases mortality and causes renal failure

According to literature:

1. Crystalloids - first preference-when available(NS,R/L)

2. Colloids –Keeping in view of adverse effects and dosage ,colloids can be given with crystalloids

3. Avoid albumin as resuscitative fluid

Essential questions before IV fluid prescription 1. Does the patient need any prescription at all today?

2. If so, does the patient need this for a. resuscitation, b. replacement of losses, or c. merely for maintenance?

3. What is the patient’s current fluid and electrolyte status a. Does the patient have a deficit or excess of Na, Cl, K or water?

4. Which is the simplest, safest, and most effective route of administration?

5. What is the most appropriate fluid to use and how is that fluid distributed in the body?

Thanks